1.
uses crt;
var a,b,h: integer;
begin
clrscr;
    writeln('===========Dien tich tam giac==========');
    write('Nhap chieu cao: '); readln(h);
    write('Nhap day: '); readln(a);
    writeln('Dien tich tam giac=',(a*h)/2:3:2);
    writeln('===========Dien tich hinh thang==========');
    write('Nhap chieu cao: '); readln(h);
    write('Nhap day lon: '); readln(a);
    write('Nhap day be: '); readln(b);
    writeln('Dien tich tam giac=',((a+b)*h)/2:3:2);
    readln
end.
2.
uses crt;
var d15,d45,dtx,dtx2,s: real;
begin
clrscr;
    write('Nhap diem 15 phut: '); readln(d15);
    write('Nhap diem 45 phut: '); readln(d45);
    write('Nhap 2 diem kiem tra thuong xuyen: '); readln(dtx,dtx2);
    s:=(s+d15+d45+dtx+dtx2)/5;
    writeln('Diem trung binh: ',s:2:2);
    if s>=8.0 then write('NX: hoc sinh gioi') else
    if (s<8.0) and (s>=6.5) then write('NX: hoc sinh kha') else
    if (s<6.5) and (s>=3.5) then write('NX: hoc sinh trung binh') else
    write('NX: hoc sinh yeu');
    readln
end.

uses crt;
var a,b,h: real;
begin
clrscr;
write ('Nhap chieu cao: '); readln (h);
write ('Nhap canh: '); readln (a);
writeln ('Dien tich tam giac: ',(a*h)/2:1:2);

readln;

clrscr;

write ('Nhap chieu cao: '); readln (h);
write ('Nhap day 1: '); readln (a);
write ('Nhap day 2: '); readln (b);
writeln ('Dien tich tam giac:',((a+b)*h)/2:1:2);
readln;
end.
--------------------------------------------------------------------
uses crt;
var m,ddd,d15,d152,s,hk: real;
begin
clrscr;
write ('Nhap diem mieng: '); readln (m);
write ('Nhap diem kiem tra 1 tiet: ');  readln (ddd);
write ('Nhap 2 cot diem kiem tra 15 phut: ');  readln (d15,d152);

write ('Nhap diem kiem tra hoc ki: ');  readln (hk);
s:=(s+m+ddd*2+d15+d152+hk*3)/9;
writeln ('Diem trung binh: ',s:1:2);
if s>=8 then write ('nhan xet: hoc sinh gioi')

else if (s<8) and (s>=6.5) then writeln ('nhan xet: hoc sinh kha')

else if (s<6.5) and (s>=3.5) then writeln ('nhan xet: hoc sinh trung binh')

else
write ('nhan xet: hoc sinh yeu');
readln;
end.